How to distinguish ectopic pregnancy

Patient's question:

How to distinguish ectopic pregnancy

Doctor's answer:

Ectopic pregnancy is also known as tubal pregnancy. Common symptoms include vaginal bleeding and abdominal pain after a missed period. Blood test results for β-hCG show slow rise, with doubling less than 66% within 48 hours, and progesterone level below 25 ng/ml (or <78.0 nmol/L), which suggests a high possibility of ectopic pregnancy.
Intrauterine early pregnancy: Vaginal ultrasound can detect the gestational sac (GS) as early as 4-5 weeks of pregnancy. The yolk sac, a marker of intrauterine pregnancy, appears as a bright echo ring-like structure within the gestational sac, with an anechoic center. By 5 weeks, the embryonic pole can be observed, and by 6 weeks, primitive cardiac activity can be seen.
It is recommended to combine blood tests for β-hCG and progesterone levels with ultrasound findings for judgment. If the gestational sac is not visible in the uterus but a mass is observed externally, ectopic pregnancy should be considered.